Virkki, Niilo. “Meiosis and Development of the Embryo Sac in Gunnera Insignis (Oersted) D.C. (Halorhagaceae)”. The Journal of Agriculture of the University of Puerto Rico 46, no. 4 (October 1, 1962): 254–268. Accessed March 28, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12344.